Tyre Warning Light.

[Patsy]

Hi all,

I'm new to BMW ownership so apologies if this is a silly question.

I've just bought a E90 320d. It's 3 1/2 years old and has been well cared for as far as I can tell.

On the way into work this morning the tyre warning light came on. I've got Continental run flats which are reasonably worn but good for another 2k miles or so. I stopped and checked them and they all feel rock hard and I can't see any (immediately obvious) problems with them.

Could it be tyre pressures perhaps? Or do these warning lights come on from time to time for no apparent reason?

Any advice gratefully received...

[bazking69]

Have you checked the pressures?
If not, there should be a button that you can hold down for a short period to reset the warning light.

[Patsy]

bazking69 said:

Have you checked the pressures?
If not, there should be a button that you can hold down for a short period to reset the warning light.

Not yet, but I will do later.

Cheers for your help.

[mike325112]

Patsy said:

I stopped and checked them and they all feel rock hard and I can't see any (immediately obvious) problems with them.

You won't feel any drop in pressure by checking the sidewall as they are heavily reinforced. You need a pressure guage to tell which one is low on pressure. Might be a punture or just low pressure

[DSM2]

The whole point of runflat (BMW use SSTs (Self Supporting Tyres) is that the sidewalls are strong enough to support the weight of the car with no air in them, hence they, obviously, 'feel' hard.

The only way is to check the pressures.

The BMW system also works off the ABS electronics so you will get a warning if one tyre is more than a few psi different from its opposite on the same axle or is significantly lower in tread depth.

[Patsy]

Thanks guys - just wondered if it was a case of 'they all do that from time to time'.

You can tell I've had a Lotus and TVR in recent years...

[DSM2]

Patsy said:

Thanks guys - just wondered if it was a case of 'they all do that from time to time'.

You can tell I've had a Lotus and TVR in recent years...

Oh no, they certainly don't do that all the time. In fact, as long as the difference across the axle doesn't get too great, your tyre pressures can fall some way and the system won't see it.

For example, I checked my tyres once and they were all about 5psi below the correct pressure (terrible, I know, but I hadn't checked for months) but as the were all within a psi or two of each other the system was oblivious!